POSITRON EMISSION TOMOGRAPHY AND FLUORODEOXYGLUCOSE STUDIES OF METABOLIC HYPERFRONTALITY AND PSYCHOPATHOLOGY IN THE PSILOCYBIN MODEL OF PSYCHOSIS

The effects of the indolehallucinogen psilocybin, a mixed 5-HT2 and 5- HT1 agonist, on regional cerebral glucose metabolism were investigated in 10 healthy volunteers with PET and [F-18]-fluorodeoxyglucose (FDG) prior to and following a 15- or 20-mg dose of psilocybin. Psychotomim etic doses of psilocybin were found to produce a global increase in ce rebral metabolic rate of glucose (CMRglu) with significant and most ma rked increases in the frontomedial and frontolateral cortex (24.3%), a nterior cingulate (24.9%), and temporomedial cortex (25.3%). Somewhat smaller increases of CMRglu were found in the basal ganglia (18.5%), a nd the smallest increases were found in the sensorimotor (14.7%) and o ccipital cortex (14.4%). The increases of CMRglu in. the prefrontal co rtex, anterior cingulate, temporomedial cortex, and putamen correlated positively with psychotic symptom formation, in particular with hallu cinatory ego disintegration. The present data suggest that excessive 5 -HT2, receptor activation results in it hyperfrontal metabolic pattern that parallels comparable metabolic findings associated with acute ps ychotic episodes in schizophrenics and contrasts with the hypofrontali ty in chronic schizophrenic patients. (C) 1997 American College of Neu ropsychopharmacology.